His greatest strength is in the world-building and especially in coming up with innovative magic systems and considering how each one would affect different aspects of the world including economy, religion, etc. That definitely outshines his "pure writing" but his writing is solid if not spectacular IMO. Also keep in mind that Elantris was his first published book and has been out for a good 10 years now. I think you'll see improvement in some of his more recent stuff.